#include "common.h"

int tribonacci(int n)
{
	if (n == 0) return 0;
	if (n == 1 || n == 2) return 1;
	int a = 0, b = 1, c = 1;
	int ans;
	for (int i = 3; i <= n; i++)
	{
		ans = a + b + c;
		a = b;
		b = c;
		c = ans;
	}
	return ans;
}